MTL - Navy Traitor, I Marry the Female Emperor To Rule the Sea - Chapter 16

As a promise, he went out into the world as an assassin. 3 years later, after becoming the Supreme Assassin, he gave up on everything he had and returned to the ranks of ordinary people. But one day, Kismet, a mystical game created by the National Research and Development had appeared.

Enigmatic hands, spectral frame, and one cunning strike just like the swing of the Grim Reaper. The Supreme Assassin takes on the mystical world, and how his legendary tales sets off, progressively ascending the altar to becoming the best.

- Description from Novelupdates

[No fixed CP + wear books + brain hole cool text + women disguised as men + group pet]

Gu Lan crossed over and became the cannon fodder of the original book disguised as a man, counterattacked the protagonist of the original book who slapped her face, and lived in a dormitory full of sickly beauties.

Until one day, she discovered that her roommates were villains from other horror novels. After discovering the secret, Gu Lan thought she would be killed, but her roommates all looked at her strangely… Contrasted with cute Zhengtai, sickly and beautiful boy, split personality school girl, cold and stern school bully, romantic and noble son who plays Shura every day field.

- Description from novelbuddy

500 years ago, Chen Xi was devoured by a crack in the void and was transported into a cultivation world.

After Reincarnating into Naruto World at the Warring State Era as an Uzumaki, Masahiko thought that he got a useless System. He lived for 48 years as a normal, below average Uzumaki Shinobi.

That changed when he finally knew how the system works the day of his 49th Birthday!

- Description from Novelupdates